滏阳河总氮测定中水样保存条件的探究

Optimization of Water Sample Preservation Method in Determination of Total Nitrogen

为研究水体总氮(TN)测定时水样的最佳保存条件,分别测量了滏阳河四个采样点水样保存条件(室温、冷藏4℃、酸化、未酸化)下保存时间为1、3、5、7d时TN浓度,并探讨了调整pH值时对水样TN测定值的影响程度。结果表明,对于采样1d内不能及时测定的水样,令水样pH值<2、运输或保存过程中冷藏(温度为4℃)保存有利于降低TN测定值损失率;酸化水样降低TN损失率是由硫酸对220、275nm吸光度的改变所致。研究结果为实验室测量总氮浓度提供了依据。

In order to study the best preservation conditions of water samples during total nitrogen（TN） determina- tion, the concentration of the TN under conditions of room temperature, refrigerated 4 ℃, acidified, unacidified was measured at 4 sampling points of Fuyang river during storage time of 1, 3, 5 and 7 days respectively. The influence of the PH value on the total nitrogen of water sample was discussed. The results show that the for water sample that can not be measured in a timely manner within 1 day, keeping the pH value of water sample within 2, refrigeration （temperature 4 ~C） during transportation or preservation is conducive to reducing the loss rate of TN measured values; The reduction of total nitrogen loss in acidified water samples is due to change in the absorption of 220 and 275 nm by sulfuric acid. The results provide a basis for the laboratory method to measure the total nitrogen concentration.